The present invention relates in general to the fitting of a wheel onto the hub of a motor vehicle. More particularly, the invention relates to a hub assembly for the wheel of a motor vehicle, of the type comprising a hub which forms a central, axial, tubular projection for insertion into a central wheel hole. The invention furthermore relates to a wheel assembly with a hub of the above-stated type.
Motor vehicle wheel hubs are known which have a central tubular projection exhibiting a cylindrical surface onto which the wheel is placed in order to center it in a preliminary phase of fitting onto the hub. The hub usually also exhibits a radial flange with axial holes into which the wheel fastening bolts are driven or otherwise fastened.
The wheel is fitted onto the hub by placing the central wheel hole over the tubular projection of the hub and passing the bolts projecting from the hub flange through corresponding axial holes in the wheel. The locking nuts are then tightened on the bolts. This tightening ensures final centering of the wheel relative to the hub, leaving a narrow circumferential gap between the cylindrical surface of the hub projection and the central wheel hole.
Motor vehicle manufacturers require to minimize radial play between the central wheel hole and the hub projection so that, with the centering achieved by said projection, the bolts are already sufficiently centered in the respective holes in the wheel, so facilitating tightening of the nuts without requiring the person fitting the wheel to lift it up in order to be able to align it with the bolts.
One general object of the present invention is accordingly to provide, in a simple and economic manner, a hub assembly capable of facilitating wheel fitting operations, whether during vehicle assembly or during the vehicle""s service life, for example in the event of a puncture or when the wheel is refitted after replacement of its tire.
A further object of the invention is to facilitate removal of the wheel from the hub, even when rust has formed at the interface between the central wheel hole and the tubular projection of the hub. Rust inevitably tends to form in said interfacial zone due to external contaminants (water, mud) which get into the above-mentioned gap. Since rust makes it difficult to remove the wheel from the hub, motor vehicle manufacturers are now requiring hub suppliers to take steps to eliminate this problem.
Various solutions for avoiding the formation of rust have accordingly been proposed. It has been attempted to avoid the formation of rust by coating the tubular projection of the hub with a layer of anti-corrosion material (applied by painting or electrochemical treatment). This has proved costly because it requires costly and bulky equipment (for cleaning the hubs, applying the anti-corrosion material and drying it) to be added to the hub production lines.
A further object of the invention is accordingly to provide a hub assembly which is not affected by the above-stated rust problem and does not require the costly coating treatments and associated equipment to avoid the formation of rust.
Some preferred embodiments of the invention will now be described purely by way of non-limiting example with reference to the attached drawings, in which:
FIG. 1 is an axial sectional view of a hub assembly according to the present invention;
FIG. 2 is a magnified sectional view of the detail indicated II in FIG. 1;
FIG. 3 is a magnified view similar to FIG. 2, but seen from an axial sectional plane angled relative to the plane of FIG. 2;
FIG. 4 is an elevational side view, on a slightly magnified scale, of a cylindrical annular element according to the invention;
FIG. 5 is a perspective view of the annular element of FIG. 4;
FIGS. 6 and 7 are axial sectional views according to angularly offset sectional planes of the annular element of FIGS. 4 and 5;
FIG. 8 is a magnified sectional view of the detail indicated VIII in FIG. 6;
FIG. 9 is a magnified sectional view of the detail indicated IX in FIG. 7;
FIG. .10 is a magnified sectional view of the detail indicated X in FIG. 7;
FIG. 11 is a magnified sectional view of the detail indicated XI in FIG. 4;
FIG. 12 is a schematic perspective view of a variant of the annular element of FIG. 4; and
FIGS. 13 and 14 are sectional schematic views, similar to FIG. 2, of two further variants of the annular element with which the hub according to the present invention is provided.